Many devices have control means which are rotated or sliding in operation. These control devices most commonly present themselves as handles which are used to control a device by pushing or sliding or rotating the handle. Valves are a common example of devices which have external control means such as handles which are used to actuate the valves. This invention can be used with many types of devices, but valves are used for illustration of a common means of application of the device.
If a valve is opened too quickly, the substance which is being transported through the system may cause harm or damage due to the sudden pressure increase. This harm or damage may be simply illustrated by a fire hose which suddenly receives water through a nozzle as a valve is opened rapidly. The sudden pressure increase through the nozzle may cause harm or injury to the person attempting to control the hose. Other appliances which are "up stream" from a valve may be damaged due to sudden pressure rises from a fluid or other material which is transported through a system.
Likewise, the sudden closing of a valve may cause similar damage due to sudden back pressure increases. If a valve is suddenly and rapidly closed, back pressure increases may cause damage and failure to pumps which are located down stream from the valve, and sudden back pressure increases may even cause pipes or lines which are in the transport system to fail due to sudden back pressure increases.